Machine tools utilizing rotating and stationary tools require periodic tool adjustment to compensate for tool wear, tool mounting variations, wear in slides, compounds and holders, etc. Minute tool adjustment is difficult to consistently achieve, and shims and manual tool anchoring bolts and the like are often utilized to produce micro tool positioning; however, such manual adjustment means are haphazard and time consuming.
It is an object of the invention to provide a machine tool adjustment capable of producing minute tool positioning rapidly, consistently and accurately.
Another object of the invention is to provide minute tool adjustment within machine tools wherein tool positioning is controlled by an electric stepping motor capable of accurate and reversible control.
Yet an additional object of the invention is to provide minute tool adjustment means capable of being incorporated into rotating boring tools and the like wherein limited space and clearance is available.
A further object of the invention is to provide a minute tool adjustment for machine tools wherein the adjustment mechanism may be incorporated within existing tool configurations, and does not require major modification of machine tool designs.
In the practice of the invention a rotatable support includes a tool carrier mounted thereon whereby rotation of the support rotates the carrier and tool. For instance, the tool may constitute a boring tool and the carrier may be of an elongated configuration for insertion into the bore of a workpiece.
A shaft concentric with the support and carrier axis is rotatable by accurately controlled drive means, such as a reversible electric stepping motor, and an eccentric connection exists between the shaft and the tool carrier. Thus, rotation of the shaft causes a lateral force to be imposed upon the tool carrier with respect to the axis of support and carrier rotation, and this force laterally deflects the tool to provide compensation for tool wear or minor dimensional tool adjustment.
In one embodiment of the invention, the outer end of the elongated tool carrier includes a cap upon which the cutting tool is mounted. The shaft extends through the carrier and includes an eccentric portion associated with the cap through a ball bearing. The shaft is supported relative to the carrier adjacent the eccentric portion by another ball bearing wherein rotation of the shaft imposes a lateral deforming force on the cap due to the eccentric portion, and this lateral force is sufficient to slightly deflect the cap to achieve the desired tool displacement.
In another embodiment of the invention, the tool carrier is in the form of an elongated lever having a free end upon which the cutting tool is mounted. The inner end of the tool carrier lever is connected to the indexable shaft by an eccentric connection whereby rotation of the shaft causes the carrier lever to pivot about a universal pivot producing a lateral deflection at the tool carrier outer end displacing the tool as desired.
The degree of eccentricity of the eccentric portions on the shaft are small wherein only minute tool movements are produced, and the energy required to produce such movement is relatively small. The practice of the invention permits very accurate tool adjustments to be made under close control.